Colorado Parks and Wildlife has advised visitors to John Martin Reservoir State Park near Hasty to avoid all contact with the Arkansas River and the reservoir beginning Monday, August 31, 2026, as 4.2 million gallons of untreated sewage spilled in Pueblo makes its way downstream.

The sewage entered the Arkansas River in Pueblo on August 26-27 and is expected to reach the reservoir by Monday morning. The park remains open, but the advisory covers swimming, wading, tubing, paddleboarding, fishing, and any other activity involving direct water contact. Visitors should also keep pets away from affected water. Warning signs will be posted at the park and around the reservoir.

Colorado Parks and Wildlife is coordinating with the Colorado Department of Public Health and Environment and CPW's Water Resources staff. CDPHE will collect water-quality samples at the park, and CPW will update the advisory as results become available.

"I'm grateful for the communication that has kept us up to speed from the onset," said Dan Kirmer, JMRSP Manager. "While we cannot fix what is coming downstream, we have an opportunity to prepare and communicate with our visitors before it arrives."

The sewage spill compounds separate water-quality concerns already affecting the park. The reservoir was recently downgraded to a yellow caution level for possible algae-producing cyanobacteria and toxins, with regular testing ongoing. Lake Hasty, a separate body of water within the park, remains under a red danger algae condition and is closed to full-body water contact after its most recent test showed levels had increased.

"Lake Hasty will not be impacted by the sewage spill, but its existing algae restrictions remain in place," Kirmer said. "We will continue testing and communicating with our visitors as conditions change."

Visitors should follow posted signs and check the John Martin Reservoir State Park webpage at cpw.state.co.us/state-parks/john-martin-reservoir-state-park for current conditions and updates.